This project is concerned with investigating: 1) the cooperative interaction between pigmented and nonpigmented cells of the ciliary epithelium in aqueous humor production; 2) the ultrastructural basis of the blood-aqueous barrier and its experimental manipulation in vivo; 3) the anatomical devices which control aqueous humor outflow at the sclero-corneal angle. Freeze-fracturing and ultrastructural tracer techniques will represent the experimental probes. The precise knowledge of the anatomical mechanisms which regulate the intraocular pressure is necessary for a better understanding of the pathogenesis of glaucomas and for devising new pharmacological methods for their control.